Add plaster of Paris powder and warm water to a mixing bowl. Stir thoroughly until the solution becomes white and frothy.
Pour the solution into the mold you have chosen. A 16 oz. mold of any shape for your plaque is adequate. Ideas include normal rectangles or squares for you to decorate, or intricate patterns for painting and displaying like roses and animal patterns.
Set the mold of liquid plaster solution in a dry place, uncovered, for up to eight hours. If you live in a humid environment, you may want to wait an additional eight hours to assure the plaster has set properly.
Tip the mold upside down over the palm of your hand to catch the plaster plaque as it slides out. Place the plaque base facing downward.
Apply a dime-sized amount of hot glue onto the top backside of the plaque you are making. Firmly press the picture hanging strip into the the glue. Hold it in place for a minute and then release. Let it dry for 10 minutes. Turn the plaque over so the front side of it can be decorated and customized according to your creative needs.